In the production of processing meat cuts, such as pork butts, existing specifications require that sufficient fat be removed from the butt to expose six to eight square inches of lean meat, while leaving xe2x85x9th to xc2xcth of an inch fat cover on the remaining curved surface of the meat cut.
Existing machines and methods for achieving the above specification involve safety hazards and inaccurate cutting which results in waste of meat product. Further, more than one trimming operation is normally required to achieve the needed specification. Existing processes are labor intensive.
Until now, the process of removing an optimal amount of fat from meat cuts such as pork butts has required a person who makes repeated cuts until the desired amount of lean meat is exposed. Often this results in waste, as it is impossible to tell without cutting into it at what depth the lean starts and the fat stops.
Previous attempts at automating this process have met with failure because of the variation in fat cover on the meat cuts. The fat cover on meat cuts typically has a layer of lean running through it, which starts about halfway between the neck and the back which is called the false lean. The fat cover is normally thinnest at the neck edge and fattest at the back edge. It is customary when preparing such meat for sale to remove a wedge-shaped piece of fat in order to expose the xe2x80x9cfalse leanxe2x80x9d. Typically in the industry, enough fat should be removed to expose at least six square inches of lean meat while leaving xe2x85x9th to xc2xcth of an inch of fat cover on the remaining surface.
It is therefore a principal object of this invention to provide an apparatus for removing a portion of fat from meat cuts which is safe, accurate, and efficient both from a standpoint of time and labor involved.
It is a further object of the invention to provide for the photometric determination of the layers of fat and lean within individual pieces of meat for the purpose of guiding the automated removal of optimal amounts of unwanted material by means of an optical device located within a specially constructed probe.
It is a further object of this invention to use either a stationary or movable blade for fat removal in accordance with a predetermined cutting profile.
These and other objects will be apparent to those skilled in the art.
A method for removing a portion of fat from meat cuts involves placing the meat on a longitudinal conveyor, pressing sensor probes into the meat to measure the thickness of fat and the location of lean therein, and then withdrawing the sensor probes therefrom. An electronic signal is transmitted from the sensor probes to a controller and encoder to determine the depth from the outer lower surface of the meat through a layer of fat therein to a layer of lean. Data taken from the foregoing step determine the desired position of the cutting blade. A predetermined amount of fat is thereupon cut from the meat by the blade. The method is used to determine in meat the layer thicknesses by recording at uniform intervals during the penetration into the meat properties of the reflected light. These properties are mapped against the distance traveled by the probe will show segment thickness.
In an alternate form of the invention, data from a sensor is sent to the control mechanism of the cutting blade. This blade may then be moved according to the information provided by the sensor. If a sensor is not used, then the operator determines the fat thickness of the butts he will be removing from and sets the blade at a position.
An apparatus for removing a portion of fat from meat cuts includes a frame and at least one sensor probe including fiber optics to permit scanning of the interior of a meat cut penetrated by the probe. Power for moving the probe into the meat is mounted on the frame along with a skinning blade mounted in a path of movement of a meat cut on the frame.
A controller on the frame takes data from the sensor probe and determines the linear depth of fat material on the meat cut and lean material in the meat cut. The controller then determines the operating position of the blade and positions the blade to effect the removal of the desired amount of fat. The cutting height of the blade is determined by the sensor.
More specifically, a meat piece is conveyed on a conveyor belt towards the cutting device. The frame supports the probes beneath the conveyor of the meat. As soon as the meat rides over the probe path, the meat pauses, an air cylinder activates and the probes penetrate the meat. The optic fibers for reception and transmission of the signals are threaded through the probes. The probes have a probe window at the distal end. An LED sends light through a first set of fibers in the probes. The receiving signals picked up by the receiving optical fibers send a message to the controller which analyzes the signals. The probes take measurements while they are engaged with the meat piece both on the up and the down stroke. After they are withdrawn and the meat piece travels further into engagement with the skinning mechanism. The signal analysis generates a message, which is used by the blade control device to raise or lower the blade from the pulling surface of the skinning mechanism, resulting in the removal of a piece composed primarily of fat.
The difference in reflected light properties between the fat and lean muscle is distinct enough that a simple probe containing optical fibers can easily distinguish between them. This information is relayed to a controller which controls the motion of a blade.
The controller makes a determination based on the registration of a large number of reflected light properties at intervals of depth in the piece of meat. In addition, all values are inserted into a suitable equation or equation system, which is a multi-variable algorithm for the calculation of layer thicknesses.
The multivariable algorithm may include a preset offset distance which accounts for the distance between the cutting blade and toothroll in the minimum cutting position, and a variable offset which can be modified by the operator to customize this product appearance according to this customer specifications.
In addition, the algorithm may include other variables to vary the desired cutting depth at different times during the cut. For example, the cutting depth may be decreased during the first one-third of the meat to increase the resulting fat depth on the finished product. During the second one-third of the meat the cutting depth may be at the calculated depth. During the last one-third of the meat, the cutting depth may be increased to remove more fat in that area.
The cutting device includes a toothroll, shoe and curved blade holder. The blade holder is fastened to a short section of the shoe. The blade holder provides the desired curved cut, while the shoe/toothroll provides the means to pull the meat through the blade. The blade height adjusting mechanism is actuated electromechanically. The toothroll and exit conveyor drive rotate continuously. The conveyor system must move the meat through the stations, and present it to the cutting device. It indexes, so the meat is stationary when being probed. The conveyor belt is modular to ensure positive indexing. The stations are marked by blue segments on the belt. The stations are a set distance apart. During indexing, the belt accelerates for a set distance, moves at a constant speed a set distance (the approximate length of the meat cut), then decelerates a set distance. The maximum, constant speed of the conveyor is set below the surface speed of the toothroll while the meat is moving through the cutting device. The conveyors must hold the meat securely during probing, and maintain its position through the cutting device so that the depth cut is consistent with the depth measured by the probe. A pivoting, flat top plate positioned just ahead of the blade alternately presses the front end and the back end of the meat into the shoe/toothroll/blade to ensure that the meat gets a good start and finish. An alternate pivoting, curved top plate is used to press the outside edges of the meat into the toothroll for better cuttinq performance.
In an alternate form of the invention, once the blade has been set the meat advances on the conveyor into contact with the blade. The blade mechanism then follows a predetermined arcuate path. This path is based on the measured fat thickness or operator setting and reflects the statistical average of fat covering the butt, which has been determined by the inventors.
The cutting device includes a toothroll, shoe and curved blade holder. The blade holder is curved to cut an arcuate line through the butt perpendicular to the direction of travel. The blade holder is fastened to a short section of shoe. The blade holder provides the desired curved cut, while the shoe/toothroll provides the means to pull the meat through the blade. The blade height adjusting mechanism is actuated electromechanically. This allows the thickness of the fat plate removed to vary from front to back and side to side. The gripper roll and exit conveyor drive rotate continuously.
The infeed conveyor system must move the meat through the stations and present it to the cutting device. The infeed conveyor at its maximum, constant speed is set slower than the gripper roll. This speed differential helps to manipulate the meat piece over the shoe and blade system for accurate fat removal. The speed differential preserves the profile of the meat by compensating for any resistance at the blade.